[Nouveau] [PATCH] drm/nouveau: bail out of nouveau_channel_new if channel init fails
Karol Herbst
kherbst at redhat.com
Sun Nov 15 19:18:45 UTC 2020
On Sun, Nov 15, 2020 at 6:43 PM Salvatore Bonaccorso <carnil at debian.org> wrote:
>
> Hi,
>
> On Fri, Aug 28, 2020 at 11:28:46AM +0200, Frantisek Hrbata wrote:
> > Unprivileged user can crash kernel by using DRM_IOCTL_NOUVEAU_CHANNEL_ALLOC
> > ioctl. This was reported by trinity[1] fuzzer.
> >
> > [ 71.073906] nouveau 0000:01:00.0: crashme[1329]: channel failed to initialise, -17
> > [ 71.081730] BUG: kernel NULL pointer dereference, address: 00000000000000a0
> > [ 71.088928] #PF: supervisor read access in kernel mode
> > [ 71.094059] #PF: error_code(0x0000) - not-present page
> > [ 71.099189] PGD 119590067 P4D 119590067 PUD 1054f5067 PMD 0
> > [ 71.104842] Oops: 0000 [#1] SMP NOPTI
> > [ 71.108498] CPU: 2 PID: 1329 Comm: crashme Not tainted 5.8.0-rc6+ #2
> > [ 71.114993] Hardware name: AMD Pike/Pike, BIOS RPK1506A 09/03/2014
> > [ 71.121213] RIP: 0010:nouveau_abi16_ioctl_channel_alloc+0x108/0x380 [nouveau]
> > [ 71.128339] Code: 48 89 9d f0 00 00 00 41 8b 4c 24 04 41 8b 14 24 45 31 c0 4c 8d 4b 10 48 89 ee 4c 89 f7 e8 10 11 00 00 85 c0 75 78 48 8b 43 10 <8b> 90 a0 00 00 00 41 89 54 24 08 80 7d 3d 05 0f 86 bb 01 00 00 41
> > [ 71.147074] RSP: 0018:ffffb4a1809cfd38 EFLAGS: 00010246
> > [ 71.152526] RAX: 0000000000000000 RBX: ffff98cedbaa1d20 RCX: 00000000000003bf
> > [ 71.159651] RDX: 00000000000003be RSI: 0000000000000000 RDI: 0000000000030160
> > [ 71.166774] RBP: ffff98cee776de00 R08: ffffdc0144198a08 R09: ffff98ceeefd4000
> > [ 71.173901] R10: ffff98cee7e81780 R11: 0000000000000001 R12: ffffb4a1809cfe08
> > [ 71.181214] R13: ffff98cee776d000 R14: ffff98cec519e000 R15: ffff98cee776def0
> > [ 71.188339] FS: 00007fd926250500(0000) GS:ffff98ceeac80000(0000) knlGS:0000000000000000
> > [ 71.196418] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
> > [ 71.202155] CR2: 00000000000000a0 CR3: 0000000106622000 CR4: 00000000000406e0
> > [ 71.209297] Call Trace:
> > [ 71.211777] ? nouveau_abi16_ioctl_getparam+0x1f0/0x1f0 [nouveau]
> > [ 71.218053] drm_ioctl_kernel+0xac/0xf0 [drm]
> > [ 71.222421] drm_ioctl+0x211/0x3c0 [drm]
> > [ 71.226379] ? nouveau_abi16_ioctl_getparam+0x1f0/0x1f0 [nouveau]
> > [ 71.232500] nouveau_drm_ioctl+0x57/0xb0 [nouveau]
> > [ 71.237285] ksys_ioctl+0x86/0xc0
> > [ 71.240595] __x64_sys_ioctl+0x16/0x20
> > [ 71.244340] do_syscall_64+0x4c/0x90
> > [ 71.248110] entry_SYSCALL_64_after_hwframe+0x44/0xa9
> > [ 71.253162] RIP: 0033:0x7fd925d4b88b
> > [ 71.256731] Code: Bad RIP value.
> > [ 71.259955] RSP: 002b:00007ffc743592d8 EFLAGS: 00000206 ORIG_RAX: 0000000000000010
> > [ 71.267514] RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 00007fd925d4b88b
> > [ 71.274637] RDX: 0000000000601080 RSI: 00000000c0586442 RDI: 0000000000000003
> > [ 71.281986] RBP: 00007ffc74359340 R08: 00007fd926016ce0 R09: 00007fd926016ce0
> > [ 71.289111] R10: 0000000000000003 R11: 0000000000000206 R12: 0000000000400620
> > [ 71.296235] R13: 00007ffc74359420 R14: 0000000000000000 R15: 0000000000000000
> > [ 71.303361] Modules linked in: rfkill sunrpc snd_hda_codec_realtek snd_hda_codec_generic ledtrig_audio snd_hda_intel snd_intel_dspcfg snd_hda_codec snd_hda_core edac_mce_amd snd_hwdep kvm_amd snd_seq ccp snd_seq_device snd_pcm kvm snd_timer snd irqbypass soundcore sp5100_tco pcspkr crct10dif_pclmul crc32_pclmul ghash_clmulni_intel wmi_bmof joydev i2c_piix4 fam15h_power k10temp acpi_cpufreq ip_tables xfs libcrc32c sd_mod t10_pi sg nouveau video mxm_wmi i2c_algo_bit drm_kms_helper syscopyarea sysfillrect sysimgblt fb_sys_fops ttm broadcom bcm_phy_lib ata_generic ahci drm e1000 crc32c_intel libahci serio_raw tg3 libata firewire_ohci firewire_core wmi crc_itu_t dm_mirror dm_region_hash dm_log dm_mod
> > [ 71.365269] CR2: 00000000000000a0
> >
> > simplified reproducer
> > ---------------------------------8<----------------------------------------
> > /*
> > * gcc -o crashme crashme.c
> > * ./crashme /dev/dri/renderD128
> > */
> >
> > struct drm_nouveau_channel_alloc {
> > uint32_t fb_ctxdma_handle;
> > uint32_t tt_ctxdma_handle;
> >
> > int channel;
> > uint32_t pushbuf_domains;
> >
> > /* Notifier memory */
> > uint32_t notifier_handle;
> >
> > /* DRM-enforced subchannel assignments */
> > struct {
> > uint32_t handle;
> > uint32_t grclass;
> > } subchan[8];
> > uint32_t nr_subchan;
> > };
> >
> > static struct drm_nouveau_channel_alloc channel;
> >
> > int main(int argc, char *argv[]) {
> > int fd;
> > int rv;
> >
> > if (argc != 2)
> > die("usage: %s <dev>", 0, argv[0]);
> >
> > if ((fd = open(argv[1], O_RDONLY)) == -1)
> > die("open %s", errno, argv[1]);
> >
> > if (ioctl(fd, DRM_IOCTL_NOUVEAU_CHANNEL_ALLOC, &channel) == -1 &&
> > errno == EACCES)
> > die("ioctl %s", errno, argv[1]);
> >
> > close(fd);
> >
> > printf("PASS\n");
> >
> > return 0;
> > }
> > ---------------------------------8<----------------------------------------
> >
> > [1] https://github.com/kernelslacker/trinity
> >
> > Fixes: eeaf06ac1a55 ("drm/nouveau/svm: initial support for shared virtual memory")
> > Signed-off-by: Frantisek Hrbata <frantisek at hrbata.com>
> > ---
> > drivers/gpu/drm/nouveau/nouveau_chan.c | 1 +
> > 1 file changed, 1 insertion(+)
> >
> > diff --git a/drivers/gpu/drm/nouveau/nouveau_chan.c b/drivers/gpu/drm/nouveau/nouveau_chan.c
> > index b80e4ebf1..a7a47b325 100644
> > --- a/drivers/gpu/drm/nouveau/nouveau_chan.c
> > +++ b/drivers/gpu/drm/nouveau/nouveau_chan.c
> > @@ -533,6 +533,7 @@ nouveau_channel_new(struct nouveau_drm *drm, struct nvif_device *device,
> > if (ret) {
> > NV_PRINTK(err, cli, "channel failed to initialise, %d\n", ret);
> > nouveau_channel_del(pchan);
> > + goto done;
> > }
> >
> > ret = nouveau_svmm_join((*pchan)->vmm->svmm, (*pchan)->inst);
> > --
> > Frantisek Hrbata
>
> Is this still planned to be applied? AFAICS this is the fix for
> CVE-2020-25639.
>
If it's urgent to get it fixed, I suggest going through the Linux
kernel or drm stable path. CCing dri-devel, Dave, Daniel and Ben.
> Regards,
> Salvatore
> _______________________________________________
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> Nouveau at lists.freedesktop.org
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>
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